L10 Skin- Struc, Func, Disords

Question 1

LO2: desc how some cars infl suscep to and/or manic of skin dis.

Answer 1

• vitiligo- autoimm de pigm. Psychosocial impact. Less obv in White.
• autoimm hair loss- alone is areata or totalis. Psychosocial, att hair follic.
• UV induced abn- sunburn white only. Freckles, aging, skin CA (basal cell carcinoma and malig melanoma). In fair skin esp blue eyes red hair. UV dam dermal Coll and elastin=photoage. Solar elastosis.
• acne
• striae.

Question 2

LO3: desc microvasc and molec struc of skin.

Answer 2

-dermis dense irreg- BV, arrector pili, sweat gl.
-epidermis- start squam kerat=keratinocytes and prods. 4 lay:
S cornermen- horny lay. S granulosum- gran lay, prots laid, cells die. S spinosum- prickle cell lay, desmosomes btw. S basale- interdigit. Keratinocytes mitosis to. Prickle where termin diff, lose divs abil and prod keratin (heterodimeric fibrous prot). Cyc 4-6wk.
-in gran lay- keratinocytes lose PM and begin diff to corneocyte. Conts keratohyalin grans=aggregs of keratins, Enzs which-deg Plip bilat (plipase), X linkers eg filaggrin aggregs keratins, involucrin forms corneocyte env.
-s corneum- Barr. Keratinocytes from basale to corneum 40d.
-other cells of epidermis-
Melanoc- dend cells neural ori. Ev 8th cell of basal lay. Spec stains. Prod melanin protec UV. Same no in black, prod more and diff breakd.
Pale skin evolved to abs UV for vit D. May melanosomes cont melanin transf to keratinoc by pigm donat inv phagoc of tips of dend procs. Melanosomes lie outer side to nuc=UV protec.
Langerhans cells- dend, BM ori. Prickle lay scatt. Spec stains. Phagoc, mig via LS. AP to T. Med imm reacts eg allerg contact dermatitis.
-dermis-epidermal junc- BM zone. Below bl of epidermis- see by PAS. Reten malig melanoc above BM=good prog.
-dermis and constits- tough, fib, vasc lay=leather.
ECM- Coll esp T1. Elastin, GS. ECM synth by fibrob scatt spindle cells.
Cells- fibrob, BV, LV, mast, nerves.
-scars- mainly Coll. Keloids if excess scar tiss prod eg infec. More in black.
-smaller BV superfic dermis eg capill, venule, arterioles. Inter connec larger BV deeper. 2 plexi contr by smooth musc. Port wine stain-congenital malform dermal BV, incr no/vasodilat.
-mast cell arnd dermal BV. T1 immed hypersensit=hist rel=plasma leak=odema, in skin= urticaria and angio-odema.
-skin append-
Hair follics and sebaceous gl= pilosebaceous unit. Germination hair bulb with capill. Hair shaft surr by sheath. Sebac gl. Arrector pili. Sebac gl ad face large and prod lot sebum. Sebaceous gl ducts ent hair follics. Acne- abn diff of sebaceous gl ducts, become obstruc. Incr sebum prod. Infec harmless bact. Puberty.
Sweat gl- eccrine coiled duct through corneum. Hyper histories-incr sweat, unkn cause. Apocrine sweat gl large- axillae, genet, submamm. Odourless, prot rich apocrine sec. Dig by cutaneous microbes=BO.
Nails.

Question 3

LO4: Desc main funcs skin.

Answer 3

• Barr- corneum prev per cut abs exog substs. Lot study as need overcome for drug abs. Disrup in dis eg scaling eg psoriasis=loss fluid, prot in serum, nutr, heat by vasodilat. Incr abs harmf agents esp drugs.
• sensat- eg leprosy minor inj not noticed=infec and loss, diab sensory neurot.
• thermoreg- vasc and eccrine sweat. Fail eg widespread vasodilat of eryhtrodermic psoriasis, inab constrict in cold=shiver and hypoth.
• psychosex communication.

Question 4

LO5: desc dis due disord struc and/or func skin compons.

Answer 4

• psoriasis- abn epidermal growth and diff, 2%. Genet infl, MHC type. Extr prolif basal lay=thick prickle lay and excess corneum (1 wk cyc)=scaling. Can be any area. Cyclosporin tx imm supp can allow CA. UV phototherap. Decr T cell resp.
• allerg contact dermatitis- med by langerhans cells. Eg nickel 10% wom.
• malig melanoma- malig growth melanocytes. Aggress neoplasm. Reten above BM good. Penet modular bad. Comm moles- benign growth of melanocytes. Diff disting.
• vitiligo- autoimm att melanocytes, us symm, loc, well demarcated de pigm. ? Neural as melanocytes from neural crest and symm.

Question 5

LO1: desc macrostruc of hum skin and how varies with site, sex, age, ethnicity, exog infl.

Answer 5

VARS:
Col- ethnicity, site eg lip and areolar, UV.
Hair- var distrib and char with site eg Palm/sole/lip none, sex, age, ethnicity.
Laxity- site, age, UV breakd Coll and elastin.
Thickn- site and func.
Oiliness- puberty, site.